26 A TEXT-BOOK OF GRASSES 
been tried along this line but with little success. The area 
involved is too large and the expense is too great. There is 
the further difficulty of finding plants better adapted. to 
the conditions than those that primarily occupied the soil. 
The plants that tend to come in to replace those sub- 
dued by grazing are usually weedy annuals that have 
little forage value. Such are the numerous species of Old 
World brome-grasses that are now so common on the 
Pacific slope and in some portions of the region to the 
east of this. There is one exception to this, the annual 
herbaceous plant known as alfilaria or ‘‘filaree’” (Hrodium 
cicutarium (L.) L’ Herit.) a member of the geranium 
family. This is an excellent forage plant and is gradually 
spreading on the ranges of the Southwest. 
The only practicable method to rejuvenate worn-out 
ranges is to give them rest. If stock is kept from them they 
will in time return to a condition of productiveness. The 
length of time necessary for an overgrazed range to recu- 
perate depends upon many conditions. If the overgrazing 
has been for a short period a single season of rest may be 
sufficient. If a considerable portion of the original vege- 
tation has been destroyed two or three seasons may be 
necessary. In the latter case the resulting vegetation will 
probably be different from the original and may be less 
valuable. Thoughtful ranchmen are learning to conserve 
their ranges by regulation and rotation and by limiting 
the stock to the carrying capacity of the range. (See 
Bur. Pl. Ind. Bulletin No. 117 and Yearbook for 1906.) 
Range grasses 
23. The wild plants upon the range, unless they are 
positively distasteful because of bitter or acrid substances 
